[PATCH] D70963: [cmake] Disable GCC 9's -Wredundant-move

[Pavel Labath via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG385ba6065a9f: [cmake] Disable GCC 9's -Wredundant-move (authored by labath).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70963/new/

https://reviews.llvm.org/D70963

Files:
  llvm/cmake/modules/HandleLLVMOptions.cmake


Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -610,6 +610,16 @@
   check_cxx_compiler_flag("-Wclass-memaccess" CXX_SUPPORTS_CLASS_MEMACCESS_FLAG)
   append_if(CXX_SUPPORTS_CLASS_MEMACCESS_FLAG "-Wno-class-memaccess" CMAKE_CXX_FLAGS)
 
+  # Disable -Wredundant-move on GCC>=9. GCC wants to remove std::move in code
+  # like "A foo(ConvertibleToA a) { return std::move(a); }", but this code does
+  # not compile (or uses the copy constructor instead) on clang<=3.8. Clang also
+  # has a -Wredundant-move, but it only fires when the types match exactly, so
+  # we can keep it here.
+  if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+    check_cxx_compiler_flag("-Wredundant-move" CXX_SUPPORTS_REDUNDANT_MOVE_FLAG)
+    append_if(CXX_SUPPORTS_REDUNDANT_MOVE_FLAG "-Wno-redundant-move" CMAKE_CXX_FLAGS)
+  endif()
+
   # The LLVM libraries have no stable C++ API, so -Wnoexcept-type is not useful.
   check_cxx_compiler_flag("-Wnoexcept-type" CXX_SUPPORTS_NOEXCEPT_TYPE_FLAG)
   append_if(CXX_SUPPORTS_NOEXCEPT_TYPE_FLAG "-Wno-noexcept-type" CMAKE_CXX_FLAGS)


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